获取操作系统底层的Icon图标

在Winform程序的开发过程中，进行遇到图和获取特定文件类型的造作系统图标的问题，以便在UI显示上能够显示出于造作系统统一的图标，来表示特定类型的文件信息。

下面分享一种实现方式，废话少说直接上源码：

///   <summary> 
    ///   Summary   description   for   ExtractIcon. 
    ///   </summary> 
    public class ExtractIcon
    {
        [DllImport("Shell32.dll ")]
        private static extern IntPtr SHGetFileInfo
        (
        string pszPath,
        uint dwFileAttributes,
        out   SHFILEINFO psfi,
        uint cbfileInfo,
        SHGFI uFlags
        );

        [DllImport("comctl32.dll ")]
        private static extern int ImageList_GetImageCount(
        IntPtr himl
        );

        [DllImport("comctl32.dll ")]
        private static extern IntPtr ImageList_GetIcon(
        IntPtr himl,
        int i,
        uint flags
        );

        [StructLayout(LayoutKind.Sequential)]
        private struct SHFILEINFO
        {
            public SHFILEINFO(bool b)
            {
                hIcon = IntPtr.Zero; iIcon = 0; dwAttributes = 0; szDisplayName = " "; szTypeName = " ";
            }
            public IntPtr hIcon;
            public int iIcon;
            public uint dwAttributes;
            [MarshalAs(UnmanagedType.LPStr, SizeConst = 260)]
            public string szDisplayName;
            [MarshalAs(UnmanagedType.LPStr, SizeConst = 80)]
            public string szTypeName;
        };

        private ExtractIcon()
        {
        }

        private enum SHGFI
        {
            SHGFI_ICON = 0x000000100,           //   get   icon 
            SHGFI_DISPLAYNAME = 0x000000200,           //   get   display   name 
            SHGFI_TYPENAME = 0x000000400,           //   get   type   name 
            SHGFI_ATTRIBUTES = 0x000000800,           //   get   attributes 
            SHGFI_ICONLOCATION = 0x000001000,           //   get   icon   location 
            SHGFI_EXETYPE = 0x000002000,           //   return   exe   type 
            SHGFI_SYSICONINDEX = 0x000004000,           //   get   system   icon   index 
            SHGFI_LINKOVERLAY = 0x000008000,           //   put   a   link   overlay   on   icon 
            SHGFI_SELECTED = 0x000010000,           //   show   icon   in   selected   state 
            SHGFI_ATTR_SPECIFIED = 0x000020000,           //   get   only   specified   attributes 
            SHGFI_LARGEICON = 0x000000000,           //   get   large   icon 
            SHGFI_SMALLICON = 0x000000001,           //   get   small   icon 
            SHGFI_OPENICON = 0x000000002,           //   get   open   icon 
            SHGFI_SHELLICONSIZE = 0x000000004,           //   get   shell   size   icon 
            SHGFI_PIDL = 0x000000008,           //   pszPath   is   a   pidl 
            SHGFI_USEFILEATTRIBUTES = 0x000000010           //   use   passed   dwFileAttribute 
        }

        private enum SHIL
        {
            SHIL_LARGE = 0,       //   normally   32x32 
            SHIL_SMALL = 1,     //   normally   16x16 
            SHIL_EXTRALARGE = 2,
            SHIL_SYSSMALL = 3       //   like   SHIL_SMALL,   but   tracks   system   small   icon   metric   correctly 
        }

        ///   <summary> 
        ///   Get the associated Icon for a file or application,
        ///   this method always returns an icon.
        ///   If the strPath is invalid or there is no idonc the default icon is returned 
        ///   </summary> 
        ///   <param name= "strPath "> full path to the file </param> 
        ///   <param name= "bSmall "> if true, the 16x16 icon is returned otherwise the 32x32 </param> 
        ///   <returns> </returns> 
        public static Icon GetIcon(string strPath, bool bSmall)
        {
            SHFILEINFO info = new SHFILEINFO(true);
            int cbFileInfo = Marshal.SizeOf(info);
            SHGFI flags;
            if (bSmall)
                flags = SHGFI.SHGFI_ICON | SHGFI.SHGFI_SMALLICON;
            else
                flags = SHGFI.SHGFI_ICON | SHGFI.SHGFI_SMALLICON | SHGFI.SHGFI_USEFILEATTRIBUTES;

            SHGetFileInfo(strPath, 256, out   info, (uint)cbFileInfo, flags);
            return Icon.FromHandle(info.hIcon);
        }

        public static int GetIconIndex(string strPath, ImageList imgList)
        {
            SHFILEINFO info = new SHFILEINFO(true);
            int cbFileInfo = Marshal.SizeOf(info);
            SHGFI flags;
            IntPtr hIcon;

            flags = SHGFI.SHGFI_SYSICONINDEX | SHGFI.SHGFI_SMALLICON;

            IntPtr ret = SHGetFileInfo(strPath, 256, out   info, (uint)cbFileInfo, flags);
            int nbIcon = ImageList_GetImageCount(ret);

            for (int i = 0; i < nbIcon; i++)
            {
                hIcon = ImageList_GetIcon(ret, i, 0);
                imgList.Images.Add(Icon.FromHandle(hIcon));
            }
            return info.iIcon;
        }
    }